This invention relates to the timed control of the flow of fluid under pressure, and more particularly to a fluid flow controller incorporating a clock timer of the wind-up spring type.
Fluid flow controllers of the prior art embody a variety of constructions and modes of operation. Those incorporating electrical timers are of complex and costly construction and may be utilized only in those situations where a source of electrical power if available and where such electrical power does not present a hazard in the environment of the fluid to be controlled.
Other types of controllers require the fluid pressure being controlled to serve the additional function of operating mechanism, such as impeller driven control gears, to shut off the timer. Controllers of this type also are of relatively complex and costly construction and may be utilized only with fluids that are not corrosive or otherwise damaging to the components of the timer and, conversely, where contamination of the fluid by direct contact therewith of the timer components, is not objectionable. This type of controller also is generally characterized by a mode of operation in which shut-off of the fluid flow is gradual, requiring a substantial period of time for completion. This gradual shut-off decreases the efficiency of the fluid pressure system with which the controller is utilized.
Further, except for the complex and costly timer systems, the fluid flow controllers of the prior art do not provide a preliminary delay time before the controller operates to open the fluid flow system.